Answers to Hands on Pg 62-65

6.5 : Movement of substances through Visking tubing
Aim : To study the movement of substances through the Visking tubing
Hypothesis : Reducing sugar molecules which are smaller than starch molecules can move across the Visking tubing.
Variables : a) MV : Contents in the Visking tubing
b) RV : Change in colour of water samples using iodine test and Benedict's test
c) FV : Temperature//volume of solution
Observation:

Boiling tube	Beginning of experiment		After 30 minutes
	Iodine test	Benedict’s test	Iodine test	Benedict’s test
A	Yellowish brown	Blue solution	Yellowish brown	Brick red precipitate
B	Yellowish brown	Blue solution	Yellowish brown	Blue solution

Discussion
1. Salivary amylase in saliva breaks down the starch into reducing sugar. The molecules of reducing sugar are smaller in size when compared with the starch molecules. Hence, the molecules of the reducing sugar move out from the Visking tubing while the starch molecules remain inside.
2. Visking tubing represent the wall of the ileum whereas the distilled water represent the blood in the blood capillary.
3. Digestion is the breaking down of complex food molecules into simpler and smaller food molecules. These smaller food molecules are small enough to move across the membrane of the ileum into the blood capillary and transported to tissues of the whole body.
Conclusion: The hypothesis is accepted. Reducing sugar molecules which are smaller than starch molecules can move across the Visking tubing.